Sound waves have three basic parameters: 1) Pitch; 2) Quality; and 3) Loudness. Pitch relates to the frequency of the sound wave. Quality is used to describe the quality of a waveform as it is perceived by a listener. Loudness relates to the physiological sensation of sound that depends on the amplitude of the sound wave.
The human ear is sensitive and may react differently to varied levels of loudness. For example, sound may be pleasant to the ear when it is at the level of normal conversation (e.g., 55 dB-65 dB) but, at a higher power, sound may be frightening or disturbing to listeners. As an example, an individual may enjoy watching television at a certain level of loudness to overcome ambient noise. However, if the individual shuts down the television, and later returns to watch television when no such ambient noise is present, the abrupt return of the television to the same level of loudness may be jarring for the individual and disturbing for others nearby.